Flush safety latch



United States Patent [72] Inventor Ralph F. Anderson Rockford, Ill. [211 App]. No. 797,923 [22] Filed Feb. 10, 1969 [45] Patented Dec. 22, 1970 [73] Assignee Keystone Consolidated Industries, Inc.

Peoria, ill. a corporation of Delaware [54] FLUSH SAFETY LATCH 8 Claims, 6 Drawing Figs.

[52] U.S. CI 292/195, 292/3363, 292/347 [51] Int. Cl. ..E05c 13/02, E05c 3/1 0 [50] Field ofSearch 292/U-376, I95, 227, 347, J4, 336.3; 70/360, (inquired) [56] References Cited UNITED STATES PATENTS 2,786,706 3/ l 957 Wright 292/3363 3,485,068 12/ l 969 Bennett 70/360 71/11. I I '1 i3 Primary Examiner-Richard E. Moore Attorney-Wilson and Geppert ABSTRACT: A flush safety latch for furnace doors or similar applications including a cupshaped housing with a radially extending flange at its open end engaged by a cover clinched thereover at the peripheral edge. A generally cup-shaped cam is positioned in the housing for limited rotation therein, and a stem secured to the cam extends rearwardly through the housing and has a latch bolt secured adjacent the rear end. A turn button in the housing is biased toward the cover and has a central portion with a driver slot exposed through an opening in the cover; the turn button being fully rotatable in the housing unless depressed by a driver into clutching engagement with the cam.

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I nace doors or the like, and more particularly to a flush safety latch which prevents a child from unlatching and opening the door.

In the concern for child safety from devices which may be inherently dangerous, such as furnaces or refrigerators, many states have legislated safety laws for the protection of children relating to safety latches or other devices to prevent children s access to the dangerous aspects of devices, such as furnaces, where a child could be seriously injured. The present invention relates to a safety latch for furnaces which complies with these safety laws.

An important object of the present invention is the provision of a flush safety latch for furnace doors or other similar applications where the latch is mounted in and flush with the furnace door or the enclosure surrounding the door and is provided with an inwardly projecting rotatable stem having a latch bolt at the inner end thereof cooperating with a flange on the doorpr enclosure to secure the door therein. The latch includes a generally cup-shaped housing having an outer radially extending flange, and a cover of a diameter slightly larger than the flange with a depending edge to be clinched overthe flange periphery.

Another object of the present invention is the provision of a flush safety latch where a housing encloses a freely rotatable turn button having a portion of its face exposed through a central opening in the housing cover. The turn button includes a driver slot in its exposed face to be engaged by a suitable driver and to be rotated and depressed by the driver for rotation of the latch bolt. If the turn button is not depressed, it is freely rotatable without turning the latch bolt.

A further object of the present invention is the provision of a flush safety latch having a novel clutching arrangement for rotation of the latch bolt. A generally cup-shaped cam is rotatably mounted in the housing and is secured to the stern carrying the latch bolt. At its outer peripheral edge, the cam is provided with spaced projections or lugs which are adapted engage notches in the peripheral edge of the turn button when depressed. A compression spring normally biases the turn button to its outer, freely rotatable position.

Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

In the drawings:

' FIG. 1 is a side elevational view of the flush safety latch of the present invention shown in operative position secured in a furnace door.

FIG. 2 is a front elevational view of the flush safety latch.

FIG. 3 is a rear elevational view of the flush safety latch.

FIG. 4 is a cross-sectional view of the latch structure taken on the line 4-4 of FIG. 3 with the stem and latch bolt shown in side elevation.

FIG. 5 is a cross-sectional view similar to FIG. 4 but showing the turn button in clutching engagement with the cam.

FIG. 6 is an exploded view of the interior latch structure with the housing cover and latch bolt stem omitted.

Referring more particularly to the disclosure in the drawing wherein is shown an illustrative embodiment of the present invention, FIG. 1 discloses a flush safety latch 10 mounted by suitable means, such as screws 11 in an opening in a furnace door 12, the latch actuating a latch bolt 14 having a camming end which engages behind a flange or abutment 13 on the enclosure for the furnace door. The latch bolt 14 may be of any suitable design and is illustrated as a U-shaped member having a base 16, a long leg 17 terminating in the camming end 15 and a short leg 18. The legs 17 and 18 have aligned openings 19 to conformably receive a polygonal stem 22 therethrough, and a clamping screw 21 a threadingly engages the base 16 and abuts thestem 22 to clamp the latch bolt 14 thereon.

As seen in FIGS. 4, 5 and 6, the latch 10 includes a generally cup-shaped housing 23 having a cylindrical sidewall 24 terminating at one end in a radially outwardly extending flange 25 having openings 26 therein, and at the opposite end in a radially inwardly extending flange 27 defining a central'circu lar opening 28. An arcuate slot 29 of an arcuate length of ap proximately is located in the flange 27 for a purpose to be later described.

A flat cover 31 for the front end of the housing 23 of a diameter slightly larger than the flange 25, includes a central opening 32 and a depending edge which is clinched over the flange 25 as at 33. The cover includes openings 34 aligned with the openings 26 in the flange 25 to accommodate the mounting screws 11.

Within the housing is a generally cup-shaped cam 35 having a cylindrical sidewall 36 terminating at one end in a radially inwardly extending flange or bottom wall 37 defining a polygonal opening 38 of a reduced size relative to the dimensions of the stem 22. A pin or projection 39 is located on the bottom wall 37 to be aligned with and project into the arcuate slot 29 so as to limit rotary movement of the cam. At the other edge of wall 36 the cam is provided a plurality of circumferentially equally spaced projections or lugs 41 extending beyond the edge of the wall 36 but spaced from the cover 31.

The stem 22, at its forward end, is provided with an enlarged stepped circular flange 42 conformably received in the opening 28 in the housing, and terminates in a polygonal end 43 of reduced dimensions to be conformably received in and project through the opening 38 in the bottom wall 37 of the cam 35. The projecting polygonal end 43 is swaged or headed to form an enlarged head 44 thus securing the stem 22 to the cam 35 (see FIGS. 4 and 5).

Als o located in the housing 23 is a generally circular tum button 45 having a central portion of substantially greater thickness to provide circular projections 46 and 47, one on each side of the turn button; the projection 46 being conformably received in the opening 32 in the cover 31 (FIG. 4). The central thicker portion is formed with a suitable driver slot 48 therein to conformably receive the end of a suitable driver 49 (shown in dotted outline in FIG. 5). The periphery of the turn button 45 is provided with a plurality of circumferentially equally spaced notches 51-conforming in number to the projections or lugs 41 on the cam 35. A compression spring 52 is received in the housing 23 with one end received within the cam 35 and the opposite end encompassing the projection 47 on the inner face of the turn button 45 to yieldably bias the turn button 45 outwardly to the position of FIG. 4.

Considering the operation of the latch, the latch 10 is mounted in a furnace door 12 as shown in FIG. 1 with the rearwardly extending stem 22 and latch bolt 14 thereon. The turn button 45 is normally biases outwardly against the cover 31 by the spring 52, as shown in FIG. 4, and is freely rotatable without affecting the latch bolt. Thus, a child could engage the driver recess or slot 48 with a driver 49 and freely rotate the turn button 45 without any attendant release of the door or damage or injury to the child.

To release the latch bolt, a driver 49 must engage the driver slot 48 and fully depress the turn button until the projections or lugs 41 on the cam 35 are received in the notches 51 in the turn button 45 to clutch the turn button and cam together (FIG. 5). If the notches 51 and lugs 41 are not directly aligned,

a slight rotation of the turn button 45 with continuing inward A pressure will align the lugs 41 and notches 51 and allow the turn button to drop onto the cam. Then rotation of the turn button 45 causes rotation of the cam 35, the stem 22 and the latch bolt 14 to latch or unlatch the furnace door. Cooperation between the projection 39 on the cam and the arcuate slot 29 in the housing limits the rotation of the latch bolt 14 to approximately 90 between latched and unlatched positions. Removal of the driver 49 releases the turn button 45 to its normal position of FIG. 4.

I claim:

l. A flush safetylatch for use on furnace doors or similar ap- 1 'plications; comprising a cylindrical housing having a bottom' flange defining a central opening, a cover secured to the end To! the housing opposite the bottom flange and having'a central opening therein, a cam rotatably mounted in said housing, a

stem secured to said cam and extending rearwardly through the central opening defined by said bottom flange, a latch bolt securedto said stem for, rotation therewith, a turn button in said housing having a central projection received by said opening in theccover, resilient means biasing the turn button I ferentially equally 4. A flush safety latch as set forth inclaim 3, in which said 1 clutching means includes a plurality of circumferentially equally spaced lugs projecting from the periphery of said cupshaped cam, and said turn button hasa plurality of circumspaced, notches corresponding to and receiving said lugs. p

5. A flush safety latch as set forth in claim 1,1 in which said bottom flange of said housing has an arcuate slot, and a protoward said cover, and clutchingrneans to operativelyponnect said turn button and said cam. 2. A flush'safety latch as set forth in claim 1, including a radialflange on theopen end of said housing, said cover having a depending peripheral flange clinched over the periphery of the'last mentioned radial flange, said radial flange and said jection-on said cam aligned with and received in said arcuate slot, said projection andslot limiting rotary movement of said cam aligned with and received cam, stern and latch bolt.

6. A flush safety latch assetforth in claim I, in whichsaid central projection on said tum button has a driver recess I cover having alignedopenings to receive suitable securing adapted to accommodate a suitable driver.

' 7. A flush safety latch as set forth in claim 1, in which said stem includes a polygonal shaft, an enlarged stepped circular flangeadjacent one end of said stem received in the opening defined by said bottom flange, the end of, said stem at the stepped flange being secured to said cam.

8. A flush safety latch as set forth in claim 6, in which said turn button is freely rotatable in said housing when engaging said cover and, to rotate said stem, =said tumrbutton is depressed into the housing to engage the clutching meansof the cam and is rotated to rotate the cam and stem.

22 3 UINITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,549,184 Dated D cember 22, 1970 Invent r-( Ralpll F. Anderson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Column 1, line 39, after "adapted" insert to line 73, after the numeral "21 cancel a Column 2, line 54, change "biases" to biased Column 4, line 11, (Claim S) cancel "cam aligned with and received".

Safiiiifl ND SEALED Amer: mmduflewhm i mm 2. H ting Offim domissioner of Patent! 

